How to dump an empty array using Symfony Yaml

Question

I'm trying to use the Symfony Yaml dump function to output some nested php array data.

use \Symfony\Component\Yaml\Yaml;

echo Yaml::dump([
    'arr'=>[],
    'foo'=>'bar',
]);

However, the dumped YAML contains an empty object:

arr: {  }
foo: bar

while I want an empty list:

arr: []
foo: bar

I tried using the Yaml::DUMP_OBJECT_AS_MAP flag, using the ArrayObject instead of array literals, and using an EmptyIterator, all to no avail.

I found two closed bugs related to this: https://github.com/symfony/symfony/issues/9870 and https://github.com/symfony/symfony/issues/15781, but the solutions there don't seem to work, or are a bit too hacky and brittle for my taste (str_replace on the YAML output, brrrr)

I have a simple testcase with what I tried so far: https://github.com/ComaVN/php-yaml-empty-array

Any suggestions on how to fix this?

what version of Symfony? I think this may have been addressed in 3.1? — craigh
– craigh, Commented Jul 21, 2016 at 18:43
I encountered it in 2.3, but the problem still occurs with the latest version of symfony/yaml (v3.1.2, see my testcase) — Roel Harbers
– Roel Harbers, Commented Jul 22, 2016 at 7:03
see github.com/symfony/symfony/pull/17578 and symfony.com/blog/… — craigh
– craigh, Commented Jul 22, 2016 at 13:52

Christian Schmidt · Accepted Answer · 2017-05-30 13:38:42Z

7

As of Symfony 3.3 (released May 2017) you can use the new Yaml::DUMP_EMPTY_ARRAY_AS_SEQUENCE option:

Yaml::dump($object, 2, 4, Yaml::DUMP_EMPTY_ARRAY_AS_SEQUENCE);

This feature was added in PR 21471.

answered Feb 22, 2017 at 11:54

Christian Schmidt

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1 Comment

Brilliant! Adding "symfony/yaml": "^3.3@dev" to my composer.json allowed me to use this feature, and thus create swagger-ui compatible yaml.

btedu · Accepted Answer · 2016-09-23 21:34:33Z

-2

Try putting that in some form quotes, so that it can be extracted at a later time?

'arr'=>'[]',

answered Sep 23, 2016 at 21:34

btedu

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